Line scan cameras or area scan cameras are used to photograph moving objects. For example, to photograph a moving object on a moving base such as a conveyer belt, the line scan camera or the area scan camera acquires image by emitting light toward the object and detects light reflected from the object.
Image acquisition technologies using the line scan cameras or the area scan cameras may be applied to logistics, factory automation (FA), and test process automation according to uses, and may have various application fields such as recognition of a position, a size, a shape, an identification mark, and a text, a defect test, and the like However, the line scan camera or the area scan camera needs a highspeed focus control capability to acquire a high quality image even when an object rapidly moves.